The present invention relates to flush valves for use in connection with toilet devices such as urinals and water closets, and more specifically, to a piston type flush valve. More particularly, the invention relates to a specific improvement in the seal between the piston and guide of the flush valve piston assembly, which seal also functions in cooperation with the piston assembly relief valve. In prior art flush valves of the type manufactured by Sloan Valve Company of Franklin Park, Illinois, the assignee of the present invention, there is a single seal which is positioned between the piston and guide of the flush valve, which seal also cooperates with the piston assembly relief valve. At times, if this seal is over-torqued when assembling the piston to the guide, the seal may wrinkle, preventing full closure of the relief valve.
The present invention improves the seal for the piston assembly by having a perimeter portion which provides a seal between the piston and its guide and an interior portion which seals at the relief valve seat. The perimeter portion and the interior portion are connected together by integral ribs which absorb any buckling force at the perimeter seal to maintain concentricity of the interior seal at the relief valve seat.
The present invention relates to piston type flush valve for use with urinals and water closets, and more specifically, to an improved dual function seal for use in the piston assembly.
A primary purpose of the invention is to provide a dual function seal for the described environment which has a perimeter portion sealing between the piston and the guide and an interior portion which seals at the relief valve seat.
Another purpose is a dual seal as described in which the perimeter portion and the interior portion are connected together by a plurality of radially extending ribs which permit a degree of relative movement between the interior and exterior portions.
Another purpose is a seal as described which maintains concentricity of the interior seal even if the exterior seal is over-torqued when assembling the piston to the guide.
Another purpose of the invention is to provide a seal for the use described which creates a semi-permanent seal at the outer perimeter between the upper and lower parts of the piston assembly for the life of the piston assembly and creates a semi-dynamic seal at the interior which allows the relief valve to move relative to its seat during the flush cycle.
Another purpose is to provide a seal for the described environment which has two separate sealing areas connected by several small integral ribs.
Other purposes will appear in the ensuing specification, drawings and claims.